around the world are gearing up for another season of hard, but exciting work
as CERN's Large Hadron Collider (LHC) begins its spring runs.
Like most great works of science, the $10B USD LHC had less than glorious
beginnings -- its 2009 debut was marked by misinformed
public outcry over the possibility that the LHC might create
"micro-black holes" (turns out such
holes would be harmless) and costly
malfunctions that set the collider's startup back a year.
But in 2010, the reactor sprung to life, successfully completely proton beam
collisions with a net energy of 7 TeV -- a new world
record. Data collected during those runs by the LHC's cutting edge
instruments confirmed decades worth of work from lower power colliders and even
provided what might be the first hints of dark
Over the weekend the collider came back online. Researchers fired 3.5 TeV
proton beams around the 17-mile (27-km) circular track, located beneath the
Swiss-French border. CERN spokesman James Gillies stated that proton beam
collisions could resume within a week.
i. Alone in the Dark Matter
Next on the agenda for the LHC is to definitively identify dark matter and
perhaps dark energy. To do that, scientists must essentially detect the
invisible -- particles that don't emit or respond to light.
Dark matter particles are thought to be composed on one higgsino, the superpartner
of the Higgs boson, and two Gauginos, superpartners of the gauge fields.
Gauge fields produce the particles that govern interactions in our
universe, including the photon, which is responsible for electromagnetic
phenomena (and allows us to view the world as we know it). Lesser-known
products of gauge fields include gluons, responsible for the strong atomic
force, and W/Z bosons, responsible for the weak atomic force.
ii. Hunt for the Higgs boson
Speaking of the Higgs boson, the legendary "God particle" is also on
the physicists to-do list (or perhaps "to detect" list) for the year.
The Standard Model of particle physics has yet to explain how the W and Z
bosons (responsible for radioactivity) have lots of mass, while other vector
bosons (photons, gluons) have virtually no mass. According to one current
theory, the Higgs boson is a special component of the W and Z bosons that lends
If the Higgs boson indeed exists and is a component of the bosons responsible
for the weak force, physicists say that it should be detectable at collision
speeds under 1.4 TeV. This would mean that Fermilab's Tevatron (soon to
close) and the LHC should both be capable of detecting the particle, though it
may take some time to spot one.
According to top physicists, if the Higgs boson is not detected by the LHC by
the end of 2012, it will, in effect be verified not to exist.
That would mean that much of the Standard Model of particle physics is
broken. If this is the case, it's back to the drawing board. Physicists
know a number of particles that exist; if the Standard Model is broken,
researchers will have to come up with new theories to categorize and explain
these particles' existence.
Argonne National Laboratory's Thomas LeCompte, who serves as the physics
coordinator for the LHC's ATLAS detector told MSNBC in an interview that the task of
sifting through the collected data accurately is daunting. Mr. LeCompte
compares it to oil prospecting, stating, "You might strike oil, but you
haven't explored the whole field."
He acknowledges that the detection of the Higgs boson is by no means a sure
thing. He comments, "We know the Standard Model is wrong at some
level. We know that something lies beyond that. The Higgs is the simplest and
most elegant way to push it to the next level, but nature may have something
else in mind."
While not finding the Higgs boson would be fundamentally
import to physics and fascinating to theoreticians, it might spell public
relations disaster for the LHC.
University of Maryland physicist Nicholas Hadley, who works with the Compact
Muon Solenoid detector, summarized at a recent press meeting, "If we don't
see it, we will be very excited, because it means that there's something very
brand-new. But to say we looked and we didn't find anything ... we'll probably
volunteer to have other people stand up here in front of you if that day comes."
iii. Real Gains
Regardless of whether they mysteries of the elusive dark matter or the Higgs
boson are solved, CERN researchers are already offering up profound and
At the American Association for the Advancement of Science's annual
meeting in Washington, the CERN physicist supervising the LHC's ALICE detector,
Yves Schutz, announced the creation of the hottest, densest form of matter on
Earth yet. States Mr. Schultz, "We have produced in the laboratory
the hottest matter ever, the densest matter ever."
Nicknamed Quark Soup (officially know as Quark-Gluon Plasma or QGP), the exotic
form of matter created by bombarding lead ions with proton beams. Quark
Soup had only been successfully created once
before on Earth ever, at the Relativistic Heavy-Ion Collider in New
Many physicists had challenged the RHIC's data as the Quark Soup behaved like a
super-dense liquid -- an unexpected result for some. Some physicists had
theorized that Quark Soup would act as a gas at hotter temperatures. But
it did not. Instead the Quark Soup remained a "perfect liquid, which
flows without resistance and is completely opaque."
The properties of the Quark Soup precisely match those predicted by a
particular superstring theory variant, dubbed AdS/CFT correspondence.
AdS/CFT addresses such arcane mysteries as quantum gravity and higher
String theories predict 11 dimensions, including the familiar three dimensions
of space and the fourth dimension, time. Under most string theory models,
the titular strings are what compose matter. These vibrating vector
trails snake through space weave complex nets and giving rise to matter,
fundamental forces, and everything else in the universe.
Traditional physicists have attacked string theory as being overly hypothetical
and unverifiable in its vague predictions. But certain refined string
theories, such as AdS/CFT could lend credibility to the field, by offering
discrete, testable conclusions.
The fact that the LHC verified one of those conclusions is noteworthy. Mr.
Schultz remarks, "I'm surprised that [string theorists] can make a
prediction and that it matches what we measured."
iv. Back to Earth -- Looking Ahead
If string theory, dark matter, and Higgs bosons are enough to make your head
spin, take comfort in some more straightforward news from the LHC.
CERN recently announced [press release] that it would be
putting off the proposed year long shutdown and update to the LHC until the end
of 2012, in lieu of the collider's success. The reactor will complete yearlong
runs this year and next.
At the end of 2012, it will be shut down and repairs will begin. These
repairs will allow the collider to operate at 7 TeV per beam -- the original
intend power for the LHC.
While most of the desired subatomic particles should be detectable at the
current power, the higher power should make certain kinds of particles easier
to detect. It also should allow for the creation of even hotter particle
mixes, further confirming or denying various theories of physics.